at the moment, tuning is just focused on Turbo dynamics and how they interact w/ each other during low and high boost. Spool characteristics using different wg set-up.....
Not focusing of how to build power........timing and etc.
UPDATE 1:Rick Gifford aka BTF (my tuner) tried a couple of set-up for the small turbo's wastegate
First one (ABSOLUTE) is with the pressure line from the GT42 discharge hooked to the top of the primary (60mm) gate. It made
19psi by 3500.
Turbine pressure is also very high, there is 8-9psi more turbine pressure then boost.
Second one is (RELATIVE), the gate is open to the atmosphere on the top of the primary gate. It spools alot slower, but it made the GT42 take over fully on the top end. Boost pressure is higher then manifold pressure, that's how big power is made. At high rpm when the GT42 is making all of the boost (only at this wg set-up), the PR of the primary stage is below zero, implying a pressure drop across the little one. This means that the little one is freewheeling in the wind at high rpm.(again, only in this wg set-up) The drop across the entire system is less then a few psi. Implying that the whole coldside flows enough for us for now.
BTF will try and set up the pnuematics to be a hybrid of absolute/relative. Start out with the gate nailed shut and then transition to full on GT42 action.
UPDATE 2:regading fuel issue we had before.......increasing the fuel pressure to commanded 18mpa fuel rail pressure and upgrading to opel injectors........we are now getting 3.4-3.8 ms at 7500 rpm! They both helped dramatically. We have way more fuel supply right now
UPDATE 3:we are adding oil scavenging system for both turbos. Thanks to TURBOWERX.COM for the sponsorship of their Exa-pump and Exa-Pure filter!!!
UPDATE 4:Now that we know that the gt2871r is not being choked by the gt4294r, and I would like to have a faster spool, we are replacing it with a gt2860r.
We will still use the Tial turbine housing of the gt2871r, since all these gt28 turbos can share turbine housings.
cfg used on this compound tuning is specific to MPVI sensors and a custom table to log afr error for the split second R4 controller (PI injectors)
